Gap seal for flaps



J1me 1948. o. E. HOLT GAP SEAL FOR FLAPS Filed June 18. 1943 INVENTOROSCAR E HO ATTORNEY Wi d 9% Patented June 29, 1948 Oscar E. Holt,Ferguson, Mo., assignor to Qurtissa corporation of Dela- Wright.Corporation ware Application-lime 18, 1943, Serial No." 491 401 lhisinvention relates to airplanes and more particularly to means forlimiting the leakage flow of air in the gap or slot passing between. astationary lifting structure :or airfoil and a movable controlstructure, suchas a flap when the movable structure is aligned orrelatively undisplaced with respect to the stationary structure.

With the present form of flap arrangements and regardless of the flightattitude assumed by the airplane, when the flaps are moved. into. aneutral 0! up position, there is considerable leakageair which passesthrough the slot between the stationary-and movable structuresregardless of how well the union of the two structures is fashioned.This passage of air through the slot is due to the large differential ofpressure between the air on the bottom face oftheliiting structure andthe air on the top face of the lifting structure. -At such times, thisleakage at the. outlet of the slot does no good since it creates greatturbulence over the upper face of the movable structure, resulting inloss of lift and in horse power loss in the propelling of the airplane.Also this air in passing through the slot often deposits icetherebetwee'n causing the movable structure to stick to the stationarystructure when its use is desired. In addition to theicefiactuallyprevent ing relative movement of the structures, it willalso, by being deposited on the hose face of the control structure,spoil the contour thereover and setup a detrimental turbulence of air.

It is 'anobject of the present invention to provide means which wil'lautomatically come intoplay uponthe movable control structure beingmoved to its position in alignment with the liftlng structure to clcseoff the 'airslot between the movable structure and the. stationarystructure.

It is another object of the invention to provide a slot closing meanswhich is resilient and adapted to be depressed upon the movable surfacebeing returned to thelevel flight or undis placed position whereby anydeviation in tolerances or wear will not greatly afieot the efficiencyofthe slot closing means. r

e According to the present invention there has been provided within theflap arch assembly of the stationary structure, a strip of, resilientmaterial, such as rubber, running coextensively therewith. Thisresilient material, upon the flap being returned to its up position, isdepressed and its shape distorted whereby the engagement of the 'fiapwith the same-is positive and the: flow at air is efficiently sealedoff; This strip extends only a small distance rearwardly of the air faceand not to such an extent as to interfere with 4 Claims. (Cl. 244-42).

the larger flow of: air through thewslott which is desired when the flapis moved: to. its? down or displaced position. a v

For other'obiects and fora. better: understand ing of the invention,reference maybe had tozthe following detailed? description taken. in:connection with the accompanying" drawing; m which;

Fig. 1 is a fragmentary view taken throughazr airtoib section at apointthereon where the flap is connected. i i l I Figa z' is aperspective view looking atthelface of-the arch assembly of. thestationary: structure and: the strip of sealing materialrunmngatherealong." Eig. 3is an enlarged sectionalvlew: showing one formof resilient material andwiththis'material depressed due to engagementof the. flap witlr the same to effect thereby .thesealing of theairslot. I i Fig. 4. is a. sectional View of a modified form- 0tresilient material also depressed as when the flap is in its'uppositionto close off the airslotr Referring now. particularly to Figs.Lamb 2, there is shown a stationary lifting or wing structure l0havinganarch assembly H within which. there is: connected a movablecontrol. structure or flap l2; upper face= l3 of :the stationarystructure It extends. considerably-rearwardly of a lower face 14thereof; The'control structure i2? has a: nose portion I 5 and betweenit and the:

arch assembly N there is, even in the best: of

designs, an :airslot or gap l6 through which-air leaks. This leakageflow of air through theairslot is greatinasmuch as there is a largedifference of pressure of the air between the-lower and upper faces ofthe stationary surfaces"); The velocity of the? air at an outlet l1atfthe. end of the upper surface 13 is high andz suchiaasuto causeconsiderable eddyingrot air above rtheiflap with consequent loss oflift.

Themova-ble structure lz is so connectedto the stationary structure byhinge elements. adapted: to extendthrough openings Win the archassembly' that the movement with thewflap unmovable structure-t2 to itsdown position causes not; only a downward movement ot' the flap, butarearward. movement so as to enlarge the width of the slot [.6 whereby agreater fiowof airmay. behadithrough the slot at atime of takeoff or:landing: when such flowais desired over the upper surface of the llapforits scavenging; action thereon to; increase lifting power thereof. Amechanism for movin the fiapds shown-at l9,;-Fig. I;

in: which there is incorporated a pair of upper and lower links 20 and2| adapted to be operated section and has its fiat face secured to awood, backing member 26 which is connected flush with the arch assemblyll. When the movablestructure I2 is in its up position, the nose portionI5 will come into alignment with the strip and' depress the same so thatit assumes the distorted form shown :by the full lines in Fig. 3. Thisis 4 for, wherein the leading edge of the flap is of convex curvatureand adapted for nesting in a recess having an upwardly and rearwardlydirected surface formed at the trailing edge of the airfoil between theupper and lower surfaces thereof, the flap being movable rearwardly toprovide a slot between the airfoil and the flap leading edgefthroughwhich air may flow upwardly and rearwardly as the flap trailing edge vis lowered and being movable forwardly to close such slot as saidtrailing edge is raised, the nose ofthe flap leading edge presenting asurface substantially normal to the direction of such for- 'wardmovement, and a resilient strip secured desirable to obtain a tightjointat 21 and to positively close off the slot l6.

In Fig. 4, there is shown another form not a strip material which is ofsimilar outside shape as the D-shaped strip 25 but of solid rubber andof such size that the wood'b'acking is not required; As the movablestructure I2 is rotated to depress the rubber, portions 29 of thematerial will. flow along the face of the nose portion l5 therebyenlarging the contacting'area between the resilient material'29 and'theface of the nose portionl5." It should be noted however, that the extentto which these strips of material project rearwardly'of thearch assemblyis small compared to'the actual 'dis tancebetween the arch assembly andthe nose face of the flap when the flap is in its down position. Thisextent is thus not such that the-great flow of air which is desiredthrough the slot at times when the flaps are down is 'greatly impeded.

It should now be apparent that there has been provided means forlimiting the flow of air through theslot between the stationarystructure and the movable structure or flap which automatically comesinto play as the movable structure is moved to its up position intoalignment'with the stationary structurefi :With such a sealingarrangement, leakage air flow is stopped and the possibility. of icebeing disposed in the slot to such aniextent as to cause themovablesurface to stick to 'thestationary surface no longer exists, nor willice be allowed to form'on the nose face ofthe movable structure such asto disrupt the flow of air over the movable structure'surface upon'thesame beini 'moved to its down'posi'tionfl While various changes may bemade in the detailedconstructiom'it shall be understood that suchchanges shall be'withi'n'the spirit and scope of the present inventionas defined by the appendedclaims. f

I claim as my invention:'

1. In an airfoil and trailingedge flap therefor, wherein the leadingedge of the flap is of convex curvature and adapted for nestingin arecess at the trailing edge of 'the airfoil between the upper andlowersurfaces thereof, the flap being movable rearwardly to provide'a slotbetween the airfoil and the flap leading edge as the traili'ng edge ofthe flap is lowered and'being movable forwardly to close such slot assaid trailing edgeis raised, a resilient strip secured along the recesssubstantially intermediate of said upper and lower surfaces for abutmentand compressi on'by the nose of the flap leading edge to seal the"closed slot upon such forward movement.

2. In 'an airfoil and trailing edge flap therealong the recess'forabutment and compression by such flap nose surface to seal the closedslot upon such forward movement.

3. In an airfoil and trailing edge flap therefor, wherein the nose ofthe flap is of convex curvature and adapted for nesting in a recessedwall at the trailing edge of the airfoil, the flap being movablerearwardly to provide a slot between the airfoil and the flapleading'edge as the flap trailing edge is lowered through which slot airmay flow upwardly and rearwarclly, the flap being movable forwardly fornesting to close suchslot as the flap trailing edge is raised, the noseof the flap and said recessed wall of the airfoil having opposed surfaceportions one of which is substantially normal to the direction of suchforward movement, and a resilient strip secured along the other one ofsaid surface portions for abutment and compression by the firstmentioned surface portion to seal the closed slot upon such forwardmovement, theface of the strip exposed to airflow when the slot is openbeing rounded to facilitate such airflow.

4.111 an airfoil'and trailingedge flap combination, a recess in thetrailing edge of the airfoil between its upper and lower surfaces, asurface of convex curvature forming the flap' leading edge, the airfoiland flap being so constructed and arranged that a slot is providedbetween the airfoil and the flap leading edge by rearward movement ofsaid leading edge when the trailing edge of the flap is lowered and thatsaid flap leading edge moves forward to nest in the recess and close theslot when the trailing edge of the flapis raised, a resilient stripsecured along the recess substantially intermediate of said upper andlower surfaces for abutment and compression by said flap leadingedgcto'seal the closed slot upon such forward movement.

OSCARE. HOLT.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS FOREIGN PATENTS Country Date Great Britain "Sept.5, 1938 Great Britain May 15, 1940 Germany Feb. 21, 1939 Number Number

